the first presidential debate tonight of campaign 2012, a debate that matches up mitt romney with barack obama. the moderator will be jim lehrer, the executive editor of the pbs news hour. this is a spin room where the media works. it will be far busier in 12 hours time. the debate itself begins at 9:00 eastern time. some 3000 reporters and support staff are expected to be on site. the university of denver otherwise known as d.u. vying for a chance to host one of these debates. we go now for some perspective on the debate and where they fit into the political process with robert anderson, a political science professor at columbia university. good morning and thanks for being with us. >> thanks for having me. >> where do debates fit in? how important is it? guest: the base can play an important role. they probably take second place to conventions. they play a much greater role in changing people's minds. they probably play a lesser role when people are finally making up their minds. also, very early in the election year, when voters are just learning, there is a lot of volatility. the deb